1. Field
The invention generally relates to methods and an apparatus for the deployment of stents, and more particularly to, methods and an apparatus for aligning and installing stents with high accuracy by proximal-to-distal deployment, enabled for accurate proximal edge placement within the lumen.
2. Related Art
Use of stents, to overcome weakness in the walls of lumens within the human body and to open up blood vessels constricted by plaque to improve blood flow, have been in existence for some time now. These stents comprise both open stents and medicated or covered stents. The accurate placement of these stents within the lumen is a very difficult, but accurate placement of these stents is important to repair any defective regions on the side wall of the lumens. In addition, stents are used to keep the blood vessels with plaque deposit open to prevent problems related to blood supply to the organs.
Many deployment devices have been developed for accurate placement of stents in human body lumens. Many of the deployment devices are used for placement of the newer self-expanding type of stents. Most placement devices have an inner catheter with a section designated to hold a crimped stent over it at the distal end, covered by an outer catheter slidably deposed over the inner catheter to hold the crimped stent in place until deployment. A guide wire through and within the inner catheter is used as a guide to insert and guide the stent deployment device to the location where the stent will be deployed. Once at the location, the outer catheter is pulled back from over the stent to expose and deploy the stent at the location. Typically, the deployment is a distal-to-proximal deployment or a central-to-edge deployment.
A major drawback of these devices is that they install the stent in the distal-to-proximal direction. There are several scenarios where the typical distal-to-proximal deployment is highly undesirable, and a means of positioning the stent to have one end at an exact proximal location, requiring a proximal-to-distal deployment, would be extremely advantageous. Placement of the proximal edge of the stent accurately at a proximal location is critical in certain scenarios, including, for example, deployment of the self-expanding stent at a location where a side branch of a lumen originates and the side branch is not to be covered; deployment of the stent so that it overlaps another previously installed stent proximally; and deployment of the stent to cover the ostia of a lumen. The proximal to distal deployment will also be very useful in iliac stenting and during Endovascular (abdominal aortic) aneurysm repair (EVAR) procedures.
Although some proximal to distal stent placement devices have been disclosed, they do not provide the ease of placement or the capability to pre-define and establish the position of the proximal edge of the stent with respect to the location of the lumen prior to deployment for an accurate proximal-to-distal placement.